Climate change and village adaptation impact on reliability of irrigation wells in China

This paper builds a water supply reliability econometric model to analyze climate changes and adaptation impact factors on water supply reliability of irrigation wells by using 100 villages’ three-year (2010–2012) field survey data of five middle and eastern provinces of China. The results show that long-run climate change factors, adaptation measures, village-level organizations of irrigation management, as well as extreme climate factors affect the water supply reliability of irrigation wells significantly. Meanwhile, there are significant differences impacting different crops and provinces. This paper suggests that agriculture meteorological disaster monitoring and warning systems should be strengthened by increasing irrigation facilities construction and maintenance, promoting reform of agricultural irrigation water management system, and developing various forms of peasant cooperation organization in order to improve agricultural production capacity to adapt to climate change.     

Globalization and natural resources: the expansion of the Spanish agrifood trade and its impact on water consumption, 1965–2010

Beginning in 1960, the Spanish agricultural sector underwent an intensive process of development, resulting in important structural changes, not only in the sector itself, but also in the relationship of the agrarian system to natural resources. These changes were closely related to the growth of per capita income and Spain’s increasing integration into international markets. In the last five decades, the volume of Spanish agricultural trade has increased strongly, with a concomitant increase in the consumption of domestic water resources, requiring the construction of water infrastructure for irrigation. This paper examines the impact on water use in Spain during a period of economic modernization and trade liberalization. More specifically, we are interested in obtaining virtual water trade flow trends and identifying the major drivers responsible for these trajectories, via a decomposition analysis. Our results point to a large increase in virtual water exports and imports, primarily driven by the scale effect, that is, by the growing integration into international markets. The composition effect and changes in water intensity entailed a moderation in water consumption.     

农业节水和南水北调对华北平原可持续水管理的影响

针对华北平原可持续水管理中存在的问题，采用MIKE SHE模型和SD模型耦合的方式，设定现状保持、农业节水和南水北调等3种情景，模拟2014~2028年农业节水和南水北调对华北平原可持续水管理的影响。结果表明：（1）农业节水的实施对华北平原可持续水管理有一定影响，模拟期末的缺水指数下降15.8%，非充分灌溉和减少灌溉量分别使得地下水储量恢复约0.06和0.12 m；（2）南水北调显著降低缺水指数（下降50.7%），地下水水位和含水层储量出现较大的恢复（含水层储量恢复1.12 m）；（3）华北平原短期内无法解决缺水问题，但通过多种途径结合，倡导节约用水，提高用水效率，引入区域外的水，可以有效地缓解华北平原的缺水问题，保证水资源的可持续利用和发展。     

Impact of climatic conditions on irrigation water requirements and hydraulic characteristics of modern irrigation systems

Irrigation system performance regards as a function of climatic conditions. The present study was carried out to study this phenomenon. Sugar beet and sesame corps were cultivated during two agricultural seasons of 2017/2018 and 2018/2019 irrigated with drip and sprinkler systems. The drip and sprinkler systems performance was evaluated in terms of hydraulic characteristics added to irrigation water requirements. The recorded monthly values were compared to the traditional estimation method. The results revealed that irrigation system efficiency was increased by increasing ambient temperature for the drip irrigation system, and vice versa was noticed with the sprinkler irrigation system. Emission uniformity and application efficiency of emitters were increased by increasing ambient temperature. While the sprinkler flow rate and distribution uniformity were decreased by increasing ambient temperature. For drip irrigation system, the average total amount of irrigation water requirements using traditional estimation for sugar beet (2372 m³/fed) was less than the actual calculated (2439 m³/fed), while for sesame crop, the traditional estimation method (2556 m³/fed) was higher than actual calculated (2477 m³/fed). Using a sprinkler system, the average total amount of irrigation water requirements by the traditional estimation (2689 and 2897 m³/fed) was less than the actual calculated (2709 and 3044 m³/fed) for sugar beet and sesame crops, respectively. So, it is important to consider the effects of climatic conditions through the agricultural season.

     

三峡库区水库水质Streeter-Phelps模型修正及COD变化规律的新探讨

水体复氧规律的研究对于预测和评价水中溶解氧含量,确定有机污染水体的自净过程具有重要意义.天然水体中溶解氧的多少是评价水环境质量优劣的一项非常重要的指标,是水质预测的一个重要任务.Streeter-Phelps模型是目前进行河流水质研究常用的物理模型,具有良好的理论和实用价值,然而在某些特定水域,该模型的应用受到限制,主要原因是复氧系数的取定多在水流速度较大情况下得到的,而未考虑水面波动对复氧系数的影响,另外,在实际研究过程中发现三峡库区COD变化的规律出现异常:在离排污口相当远的水域,COD随时间变化趋势并不是指数衰减,而是在某个常值附近微小摆动,以往很多修正过的Streeter-Phelps模型都无法解释这个现象.经研究表明:考虑波动效应后,对复氧系数进行修正能得到较好的模型计算结果;同时,COD变化规律不仅可以弄清楚,而且可以为进一步研究排污规律和泥沙运动提供科学依据.     

湘南红壤丘陵区农户经济行为对土地退化的影响分析——以祁东县紫云村为例

通过在湖南省祁东县紫云材进行的土地利用及农户经济行为调查,从土地状况、从业选择、农具、农田设施、耕作方式和效益等方面,分析了湘南红壤丘陵区农户社会经济行为对土地质量的影响。结果表明：紫云村农户重“品种”轻“土壤”,水田土壤有机质含量减少,理化性状变差,土壤自然肥力降低,旱地、林地粗放经营,质量退化。改变农户只重“品种”而忽视“土壤”的观念、提高耕地复种指数、建立合理的轮作体系和水土保持型高效集约持续的耕作制度、加强林业管理和经营、加大农业投入、搞好农田水利建设是防止本区土地退化和保证本区农业可持续发展的对策。     

干旱灾害对江西省农业生产的影响及其对策

江西是农业大省，是国家重要的粮食主产区。近10 a来江西省干旱发生频繁，导致农业生产损失严重，威胁到农业的可持续发展。基于历史文献与资料，结合江西省农业厅的农业灾情调查数据和干旱指数最高的星子县、都昌县调研数据，着力分析近10 a来江西省的干旱状况及其对农作物生产的影响，探讨农业干旱灾害的成因。研究结果表明:江西干旱灾害以秋旱为主，近10 a年对江西的粮食和棉花生产造成重大损失，尤其是鄱阳湖区地区；江西农业干旱灾害的主要成因包括降水分布不均匀、红壤持水能力低、水利设施年久失修、植被结构破坏和易改变水文过程的大型水利设施建设。最后针对农业干旱灾害的主要成因，提出了减轻干旱灾害对农业生产不利影响的对策     

气候变化下21世纪上海长江口地区降水变化趋势分析

近百年来,以全球变暖为主要特征的气候与环境发生了重大变化,在此条件下,气候变化对自然生态系统的影响越来越大,特别是对水资源的负面影响尤为明显,包括水资源数量、质量及其时空分布,水资源开发利用程度,供用水结构以及产水、供水、用水、耗水、排水之间的关系等。上海长江口地区是我国经济发展核心区,而南水北调东线工程实施后,长江口的流量,以及海水的入侵都会直接影响到上海的发展,因此未来百年该区域的降水量在气候变化影响下的变化趋势对区域发展有着一定的影响作用。利用IPCC 数据分发中心提供的CCCma模式的4种模拟结果,分析了在全球气候变化下,由于人类活动影响、温室气体增加等共同作用时,长江口地区未来50～100年的降水量变化情景。结果表明,降水量总的会呈现上升趋势,并且降水强度的变化也越来越明显。     

长江流域农业用水效率研究:基于超效率DEA和Tobit模型

提高农业用水效率对于农业可持续发展和保障粮食安全具有重大意义。考虑降雨量中绿水资源对农作物生长的重要性,将绿水资源纳入农业用水总量,全面分析长江流域农业用水效率变动趋势。基于1998~2011年长江流域10个省份的面板数据,运用超效率DEA和Tobit模型对流域农业用水效率进行了测度和影响因素的检验。研究发现:(1)在研究期间内,长江流域农业用水效率呈现出波段式上升态势;流域各区段的用水效率呈下游、上游、中游依次递减的区域分布格局。(2)灌溉费、节水灌溉技术和农业对外开放度对流域农业用水效率有显著的正向效应;人均水资源量和年降水量均对流域农业用水效率有负向关系,但只有降水量在统计上显著。研究结果表明应当提高长江流域,尤其是中上游水资源禀赋较高地区的农业用水效率;在农业节水的具体政策方面,调整农业灌溉水价、加强农业技术创新能力和扩大农业经济对外开放程度能够取得较为显著的节水效应。     

南京地区农业耗水量估算与分析

结合南京地区的农业生产状况 ,采用Penman -Montieth法计算参考作物的潜在蒸散 ,建立了本地区农业耗水的物理模型 ,计算了南京地区历年的农业用水量 ,并根据实际资料对模型进行了检验 ,结果表明该模型具有较高的精度 ,能够反映农业用水的实际情况。在分析该地区历年农业用水量变化及其用水现状的基础上 ,对影响农业用水量的因素和该地区的农业用水效率进行了分析和计算。南京地区农业用水量的大小很大程度上取决于耕地面积和各类作物播种面积的变化 ,同时也受当年气候状况的影响。南京地区多年的农业用水效率计算结果表明 ,该地区的灌溉水利用率较低。最后对该地区的水资源可持续利用提出了相应的建议     

Performance of a hybrid solar collector system in days with stable and less stable radiative regime

The aim of this work is to analyse the performance of a solar energy collector system for water and air heating in real working conditions. Two coupled mathematical models have been developed. One of them describes the thermal behaviour of the Hybrid Solar Collector (HSC) and the second one describes the simultaneous operation of the HSC and of a fully mixed water storage tank. The dependence of the performance of the HSC system on the following three parameters has been studied: (1) water and air mass flow rate; (2) water pipe diameter and air channel height; (3) water storage tank volume. The mathematical models were used to evaluate the HSC system performance during 29 different days, covering all four seasons. A higher water flow rate generally enhances the thermal efficiency of the HSC system, but the enhancement became significantly smaller at higher air flow rates. Positive but small values are recommended for the difference between the fluid temperature at solar collectors exit and the water temperature in the tank. The thermal efficiency of the HSC system is higher on nearly clear sky and decreases in case the amount of clouds on the sky increases.     

湖北省湖库洪水调蓄能力及其空间分异特征

湖泊是抵御湖区水系洪水灾害的天然屏障，而水库是现代防洪工程体系的重要组成部分，两者共同肩负着防洪减灾的重任。为探明湖北省湖库洪水调蓄能力，选取湖泊可调蓄水量、水库防洪库容作为评估指标，通过构建湖库洪水调蓄能力评估模型，分析全省湖库洪水调蓄能力及空间分异特征。结论如下：（1）湖北省湖泊、水库综合洪水调蓄量为416.02×108m3，其中湖泊可调蓄水量为79.69×108m3，水库防洪库容为336.33×108m3，分别占湖库洪水调蓄功能总量的19.16%和80.84%;（2）湖泊可调蓄水量较大的地区包括武汉、荆州、鄂州、黄石等地市以及鄂东丘陵、江汉平原，而单位面积湖泊调蓄洪水能力较强的地区为鄂州、黄石、咸宁、黄冈，其值分别为405.99×104、400.31×104、392.32×104和391.22×104m3/km2;（3）水库防洪库容较大的地区主要为鄂西山地的宜昌和十堰，分别为119.18×108m3和 103.03×108m3，占全省防洪库容总量的66.06%，而鄂州、天门和神农架水库防洪库容极小，不足全省水库总防洪库容的1%;（4）湖库综合调蓄能力空间分布特征与水库洪水调蓄能力空间分布相一致；从湖泊、水库洪水调蓄能力的构成来看，以湖泊防洪为主和以水库防洪为主的地市不相上下，水库在湖北省防洪体系中占绝对主体地位，同时湖泊也发挥着不可或缺的作用。针对湖泊萎缩、水库险病等突出问题，可以通过退田还湖、除险加固等工作提高湖库综合调洪能力。本研究可为湖北省湖库防洪建设提供科学指导。 关键词： 湖泊；水库；洪水调蓄功能；空间分异；湖北省     

葛洲坝对长江径流过程的影响

水流是河流生境的主要决定因素之一，影响生物群落的组成和多样性。河流径流过程及特征可以通过水文参数值及其统计特征来反映，包括水文值的大小、发生时间、持续时间、发生频率和变化特征等。水利工程会改变河流天然径流过程。采用IHA法对葛洲坝的河流径流过程影响进行了评价，结果显示总体上葛洲坝水利枢纽对河流天然径流的改变不大，但其一定的削峰坦化作用可能是上涨率和下降率等参数值在建坝后发生一定变化的原因。     

Relations between Agricultural Natural Disasters and Rural Poverty Based on Analysis of Panel Data in Anhui Province,China

The occurrence of natural disasters has a tremendous negative effect on agricultural production. The effect of natural disasters in undeveloped areas is more serious and even leads to the occurrence of poverty due to the weak capacity to handle these disasters. Although there is much research based on qualitative analysis, the quantitative research is rare. This article aims to cover the previous quantitative research gap. On the basis of the analysis of panel data in Anhui province, it is evident that there is a negative correlation between the proportion of the area affected by agricultural natural disasters to the total sown area and the incidence of rural poverty, which is not compatible with the previous studies. Therefore, the authors make a possible explanation. On the basis of the empirical results, some policies are recommended in the final part of this article on a correct understanding of agricultural natural disasters and rural poverty, such as building a rural natural defense system and strengthening the response capacity of farmers in impoverished areas.     

Opportunity to restore irrigation tanks in the Cauvery delta by mining and deepening

Delta region of the Cauvery river in India is well known for paddy cultivation for centuries. Due to increased competition on river water sharing over the past century, availability and reliability of water in this region is dwindling. Changes in management practices, which caused the deterioration of traditional tank (relatively small reservoir) irrigation systems, and the difficulties in reviving them are discussed. Increasing the storage capacity of irrigation tanks for augmenting water availability for irrigation is discussed in detail. Managing the huge cost involved in deepening the heavily silted tanks in a sustainable manner is suggested through allowing mining activities in the tanks. Sample study on the suitability of soil for commercial uses indicates the possibility of mining in the tanks.     

长江河口淡水资源利用与避咸蓄淡水库

开发利用长江口的淡水资源,首先要研究河口水质的污染程度以及咸潮入侵的时空变化规律。长江河口水质除边滩存在局部污染外,主槽水质良好。长江口南支、南港、北港盐水来源主要有北支倒灌和外海盐水直接入侵两种形式,盐水入侵具有周日、半月、季节和年际变化规律,由于北支倒灌咸水团的影响,低盐度值往往出现在大潮期和涨憩附近,通过修建边滩水库,达到控制引水时间、避咸蓄谈的目的。最长连续超标天数的推算是确定水库库容的关键问题,采用数理统计、二维数值模拟、ARMAX模型＋Markov模型等方法推算,几种方法相互印证,计算结果基本上符合实际情况。“避咸潮取水,蓄淡水保质”,这是宝钢干部、科技人员总结出来的长江河口引水经验。长江口取水工程由取水系统、调蓄水库和输水系统等三大部分组成。长江口避咸蓄淡水库的成功经验,对沿海潮汐河口的淡水资源开发利用具有示范作用。     

Assessing groundwater quality and its sustainability in Joypurhat district of Bangladesh using GIS and multivariate statistical approaches

Sustainable groundwater quality is a key global concern and has become a major issue of disquiets in most parts of the world including Bangladesh. Hence, the assessment of groundwater quality is an important study to ensure its sustainability for various uses. In this study, a combination of multivariate statistics, geographical information system (GIS) and geochemical approaches was employed to evaluate the groundwater quality and its sustainability in Joypurhat district of Bangladesh. The results showed that the groundwater samples are mainly Ca–Mg–HCO₃ type. Principal component analysis (PCA) results revealed that geogenic sources (rock weathering and cation exchange) followed by anthropogenic activities (domestic sewage and agro-chemicals) were the major factors governing the groundwater quality of the study area. Furthermore, the results of PCA are validated using the cluster analysis and correlation matrix analysis. Based on the groundwater quality index (GWQI), it is found that all the groundwater samples belong to excellent to good water quality domains for human consumption, although iron, fluoride and iodide contaminated to the groundwater, which do not pose any significant health hazard according to World Health Organization’s and Bangladesh’s guideline values. The results of irrigation water quality index including sodium adsorption ratio (SAR), permeability index and sodium percentage (Na %) suggested that most of the groundwater samples are good quality water for agricultural uses. The spatial distribution of the measured values of GWQI, SAR, Fe (iron), EC (electrical conductivity) and TH (total hardness) were spatially mapped using the GIS tool in the study area.     

长江河口淡水资源利用与避咸蓄淡水库

开发利用长江口的淡水资源 ,首先要研究河口水质的污染程度以及咸潮入侵的时空变化规律。长江河口水质除边滩存在局部污染外 ,主槽水质良好。长江口南支、南港、北港盐水来源主要有北支倒灌和外海盐水直接入侵两种形式 ,盐水入侵具有周日、半月、季节和年际变化规律 ,由于北支倒灌咸水团的影响 ,低盐度值往往出现在大潮期和涨憩附近。通过修建边滩水库 ,达到控制引水时间、避咸蓄淡的目的。最长连续超标天数的推算是确定水库库容的关键问题 ,采用数理统计、二维数值模拟、ARMAX模型 +Markov模型等方法推算 ,几种方法相互印证 ,计算结果基本上符合实际情况。“避咸潮取水 ,蓄淡水保质” ,这是宝钢干部、科技人员总结出来的长江河口引水经验。长江口取水工程由取水系统、调蓄水库和输水系统等三大部分组成。长江口避咸蓄淡水库的成功经验 ,对沿海潮汐河口的淡水资源开发利用具有示范作用。     

望虞河引清调水改善太湖水环境定量分析

以望虞河引清调水实践为背景，利用引水调水现状及实测数据，建立适合太湖的二维水量水质数学模型，并模拟计算调水前后湖体各项水质因子浓度的空间变化规律。结果显示：水利调度影响下太湖湖体中高锰酸盐指数、氨氮、和总氮的浓度大体上有所减小，改善率分别为60%、160%和92%，总磷稍有反弹，其指标恶化了44%，太湖湖体水质总体改善面积37%，主要集中在贡湖、梅梁湖及东部湖区这些引排水水流流经的区域，表明“引江济太”调水工程对改善太湖局部湖区水质、保障太湖供水安全具有重要意义，可为其他类似水域的水污染治理提供科学参考和依据     

农业自然灾害与农村贫困之间的关系——基于安徽省面板数据的实证分析

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